It happened 50 years ago today. The moment was captured by ringside photographer Neil Leifer and the photo became one of the most iconic images in the world.

What many don't know is the pic was taken moments after what is believed to be the most controversial punch in boxing history - and perhaps one of the most contentious moments in all of professional sports.

Date: May 25 1965

Location: St. Dominic's Hall, Lewiston, Maine, USA

Referee: Jersey Joe Walcott

Division: Heavyweight

Title: World/Lineal (Ali defending)

Ali vs Liston 2: Facts, Stats & Video

The ending of the rematch between Muhammad Ali and Sonny Liston remains one of the most controversial in boxing history.

Midway through Round 1, Ali appeared to have struck Liston with a short shot on the inside. Liston fell to the canvas like a felled ox, then struggled to his knees only to roll back and fall again.

Chaos ensued as Referee Jersey Joe Walcott appeared confused after Ali, instead of going to the neutral corner, initially stood over his fallen foe, yelling at Liston, "Get up and fight, sucker!"

As Walcott attempted to take control of the situation, 20 seconds passed. Liston, by then, had arisen and the fighters resumed boxing. However, Nat Fleischer, publisher of The RING Magazine who was sitting at ringside, beckoned Referee Walcott over to tell him Liston had been on the canvas well over 10 seconds. As a result, Walcott stopped the fight, giving 'The Greatest' a first-round knockout.

Dubbed the 'Anchor Punch' by Ali, the blow that ended the match became known as the 'Phantom Punch' by doubters who claimed it was not legit, insisting that Liston took a dive. After all, the brutish Liston who was known for his durability.

Ali stated he learned how to unleash the 'Anchor Punch' from famous Hollywood actor Stepin Fetchit, who was believed to have learned it from heavyweight great Jack Johnson.

Did Liston take a dive? Given his link to organized crime (which was well-known even then) some say the mafia forced him to take a dive as part of a betting coup. Even the details surrounding his death 5 years later are sketchy.

Moreover, Liston was purportedly threatened by members of the Nation of Islam who allegedly promised a bullet would be waiting for him if he was victorious.

What really happened that day in Lewiston, Maine is still debated to this day.

Side note: Singer Robert Goulet mangled the lyrics to the United States National Anthem

Quotes

"It was a perfect punch."- Fight legend Joe Torres

"The blow had so much force it lifted Liston's left foot, upon which most of his weight was resting, well off the canvas."-Tex Maule of Sports Illustrated

"C'mon. Here was a guy who was in prison and the guards use to beat him over the head with clubs and couldn't knock him down."- Hall of Fame announcer Don Dunphy